// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_TOOLS_QUIC_TEST_TOOLS_MOCK_EPOLL_SERVER_H_
#define NET_TOOLS_QUIC_TEST_TOOLS_MOCK_EPOLL_SERVER_H_

#include <stddef.h>
#include <stdint.h>

#include <unordered_map>
#include <unordered_set>

#include "base/logging.h"
#include "base/macros.h"
#include "net/tools/epoll_server/epoll_server.h"
#include "testing/gmock/include/gmock/gmock.h"

namespace net {
namespace test {

    // Unlike the full MockEpollServer, this only lies about the time but lets
    // fd events operate normally.  Usefully when interacting with real backends
    // but wanting to skip forward in time to trigger timeouts.
    class FakeTimeEpollServer : public EpollServer {
    public:
        FakeTimeEpollServer();
        ~FakeTimeEpollServer() override;

        // Replaces the EpollServer NowInUsec.
        int64_t NowInUsec() const override;

        void set_now_in_usec(int64_t nius) { now_in_usec_ = nius; }

        // Advances the virtual 'now' by advancement_usec.
        void AdvanceBy(int64_t advancement_usec)
        {
            set_now_in_usec(NowInUsec() + advancement_usec);
        }

        // Advances the virtual 'now' by advancement_usec, and
        // calls WaitForEventAndExecteCallbacks.
        // Note that the WaitForEventsAndExecuteCallbacks invocation
        // may cause NowInUs to advance beyond what was specified here.
        // If that is not desired, use the AdvanceByExactly calls.
        void AdvanceByAndWaitForEventsAndExecuteCallbacks(int64_t advancement_usec)
        {
            AdvanceBy(advancement_usec);
            WaitForEventsAndExecuteCallbacks();
        }

    private:
        int64_t now_in_usec_;

        DISALLOW_COPY_AND_ASSIGN(FakeTimeEpollServer);
    };

    class MockEpollServer : public FakeTimeEpollServer {
    public: // type definitions
        using EventQueue = std::unordered_multimap<int64_t, struct epoll_event>;

        MockEpollServer();
        ~MockEpollServer() override;

        // time_in_usec is the time at which the event specified
        // by 'ee' will be delivered. Note that it -is- possible
        // to add an event for a time which has already been passed..
        // .. upon the next time that the callbacks are invoked,
        // all events which are in the 'past' will be delivered.
        void AddEvent(int64_t time_in_usec, const struct epoll_event& ee)
        {
            event_queue_.insert(std::make_pair(time_in_usec, ee));
        }

        // Advances the virtual 'now' by advancement_usec,
        // and ensure that the next invocation of
        // WaitForEventsAndExecuteCallbacks goes no farther than
        // advancement_usec from the current time.
        void AdvanceByExactly(int64_t advancement_usec)
        {
            until_in_usec_ = NowInUsec() + advancement_usec;
            set_now_in_usec(NowInUsec() + advancement_usec);
        }

        // As above, except calls WaitForEventsAndExecuteCallbacks.
        void AdvanceByExactlyAndCallCallbacks(int64_t advancement_usec)
        {
            AdvanceByExactly(advancement_usec);
            WaitForEventsAndExecuteCallbacks();
        }

        std::unordered_set<AlarmCB*>::size_type NumberOfAlarms() const
        {
            return all_alarms_.size();
        }

    protected: // functions
        // These functions do nothing here, as we're not actually
        // using the epoll_* syscalls.
        void DelFD(int fd) const override { }
        void AddFD(int fd, int event_mask) const override { }
        void ModFD(int fd, int event_mask) const override { }

        // Replaces the epoll_server's epoll_wait_impl.
        int epoll_wait_impl(int epfd,
            struct epoll_event* events,
            int max_events,
            int timeout_in_ms) override;
        void SetNonblocking(int fd) override { }

    private: // members
        EventQueue event_queue_;
        int64_t until_in_usec_;

        DISALLOW_COPY_AND_ASSIGN(MockEpollServer);
    };

} // namespace test
} // namespace net

#endif // NET_TOOLS_QUIC_TEST_TOOLS_MOCK_EPOLL_SERVER_H_
